On printed media such as books, magazines, and brochures, for example, in the form of machine-readable dot patterns, stored (printed) data may be used, for example, to provide the reader of a printed medium with additional information. This additional information may be, for example, information that cannot be represented on printable media, such as movies or music, for example, or more extensive information that in principle could be represented on the printed medium, but cannot be accommodated in the printed medium because of its volume.
The dot pattern may represent the additional information itself, or may represent a link to the additional information located elsewhere, for example stored on a CD or a computer or retrievable via the internet.
In one possible practical application, next to an entry about a composer in an encyclopedia a dot pattern is printed that represents a link to a piece of music by the composer stored on a CD. If the information about the composer provided in the text is not sufficient for the user of the encyclopedia, the user may obtain additional information via his computer, and may replay the referenced piece of music, for example. For this purpose he connects an optical-dot-pattern reader to his computer, and uses it to scan the dot pattern printed next to the article about the composer and sends it to the computer. The computer or special software installed thereon decodes the dot pattern, and, depending on the content of the decoded data, automatically starts further actions such as playing the piece of music, for example.
Another practical application is a catalog of a travel agency. If one were to include in such a catalog all the details about all trips offered by the travel agency, a catalog would result that would be so large and so expensive to produce that it would not be suitable for distribution to the public. In addition, such a catalog would become outdated very quickly due to changes in fares, new trips included in the offered selection, trips no longer offered, travel schedules no longer current, etc., and updated editions would have to be reprinted within very short time intervals. This may all be avoided by including in the catalog only the base information that does not change or that changes infrequently, and providing the more detailed description of the particular trips as well as the quickly changing information such as travel fares, schedules, etc. via an internet link represented by a dot pattern. The reader of the brochure may initially choose from the catalog the trips of interest, and may then download additional information from the internet, and optionally even make a reservation over the internet. For this purpose he connects his computer to an optical-dot-pattern reader that he uses to scan the dot pattern printed next to the particular travel offer, and sends it to the computer. The computer or special software installed thereon decodes the dot pattern, and depending on the content of the decoded data automatically starts further actions such as, for example, downloading and displaying the desired additional information from the internet.
The size and number of dots of the dot pattern are preferably very small in order to eliminate or at least minimize an objectionable appearance on the printed medium. To ensure that the dot pattern occupies as little space as possible on the printed medium and that a small and inexpensive dot-pattern reader may be used, the spacing between the dots of the dot pattern should also be very small. Despite the dots being as few as possible in number and having the smallest possible size, with small spacing between the dots, it must be possible to reliably print, scan, and decode the dot pattern without errors, this preferably also applying when nonoptimal conditions are present, for example when the size, the spacing, and/or the relative position of the dots with respect to one another deviate or vary from the set-point values due to printing problems, or when the dot pattern is scanned with distortions due to a curvature in the printed medium and/or a nonoptimal position or alignment of the dot-pattern reader.
A method as described above is known from EP 03 710 388 A1, for example. However, the method described in this document does not meet all the prerequisites stated above for reliable, error-free use of this method, also under unfavorable conditions.
A remedy is also not provided by the method described in DE 102 55 926 A1 [U.S. Pat. Nos. 7,726,570, 7,669,774, and 7,328,845), in which the data to be stored are stored in the form of a line pattern.
In the conventional storage and reading methods, the necessary precision in positioning the dot patterns for reproducibly reading the data requires the use of offset printing and hard master copies. Digital printing such as laser printing or ink-jet printing, for example, are not able to ensure the desired precision in the positioning or resolution, since for ink-jet printing even the smallest droplets of ink of the latest product generation on the print media result in excessively large dimensions of the print dots, and for laser printing the print dots have excessively large dimensions due to the electrostatic repellence of the particles.